Less Vascular-Dense Choroid Associated With Ischemic Optic Neuropathy

Massachusetts researchers suspect there may be an anatomic predisposing element to the pathogenesis of non-arteritic anterior ischemic optic neuropathy (NAION). Their research, presented at the North American Neuro-Ophthalmology Society (NANOS) 2021 Annual Meeting, held virtually February 20 to 23, 2021, investigated the relationship between peripapillary choroidal thickness and ratio of vascular to total choroidal area in eyes with NAION compared with healthy eyes.

The investigators used imaging, including swept-source optical coherence tomography (SS-OCT), to uncover variations in peripapillary choroidal thickness and choroidal vascular index (CVI) in 17 eyes with acute or non-acute NAION, 6 unaffected fellow eyes, and 18 eyes of 18 healthy control group participants. This is the first study to evaluate the interaction between peripapillary choroidal thickness and CVI, and to explore possible correlation of choroidal vascular structure and function in eyes with NAION, according to the study.

Imaging presented in fundus photos displayed a grid of peripapillary choroidal thickness values overlying a circular grid around the optic nerve. Structural layers viewed in binarized SS-OCT B-scans illustrated the luminal area and stromal/interstitial spaces, allowing calculation for the amount of luminal to total area.

Eyes with NAION exhibited significantly greater peripapillary choroidal thickness compared with control eyes in both hemifields and quadrants, as did the temporal quadrant of fellow unaffected eyes (P <.05). Researchers found that greater thickness corresponded with lower ratio of vascular area to total choroidal area in acute NAION eyes (P <.05), but not in nonacute NAION eyes, unaffected fellow eyes, or controls (P ≥.12). Nasal CVI correlated directly with perimetric performance in nonacute NAION (r²=0.63, P <.02, but not in acute NAION (r=-0.3) or fellow eyes (r²=0.65, P values ≥.06), the study adds.

Overall, peripapillary choroidal thickness was higher in NAION eyes than controls (P <.008), and CVI was lower (P <.0008). Results indicate there may be a structural predisposing element to help predict potential NAION. Researchers suggest their findings agree with prior theories that propose compressive/compartment syndrome and direct ischemia contribute to the development of NAION.

Greater peripapillary choroidal thickness with decreased vascular density may be found in both eyes with NAION and potentially in unaffected fellow eyes. Also, “perimetric performance was directly associated with vascular density in non-acute NAION,” according to the investigators.

Reference

Lu ES, Cohen DA, Katz R, et al. Peripapillary choroidal vascularity and visual correlates in NAION. Presented at: North American Neuro-Ophthalmology Society Annual Meeting; February 20-23, 2021; Poster 92.